SimpleCache: Track mass dooms as pending dooms.

By placing entries being doomed in mass dooms into
entries_pending_doom_, we avoid racing operations on individual
entries with mass operations.

R=pliard@chromium.org, rdsmith@chromium.org, pasko, rdsmith, ttuttle
BUG=289542,294186

Review URL: https://codereview.chromium.org/23437030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224543 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224543
Add a container window to host the desktop window hierarchy in AURA.

This ensures that ZOrder changes within this hierarchy don't affect the ZOrder of windows like tooltips
which are direct children of the root.

This change fixes the issue with the tooltips getting hidden behind the browser window during a tab drag drop
operation.

Reverted the earlier fix in tooltip_controller.cc which destroyed the tooltip when the mouse left the window
bounds. While that works this appears to be a cleaner fix based on a discussion with sky.

I disabled the PopupBlockerBrowserTest.WindowFeatures test on linux aura as it fails for some reason
with this change. Logged a bug to track that https://code.google.com/p/chromium/issues/detail?id=295299

BUG=292530
R=ben@chromium.org
TBR=sky
TEST=Covered by new views unittest TooltipAtTopOfZOrderAfterActivation

Review URL: https://codereview.chromium.org/23903056

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224544 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224544